The inventive concepts described herein generally relate to semiconductor devices, and more particularly, to e-fuse structures of semiconductor devices.
In semiconductor device technologies, fuses are used for a variety of purposes. For example, to improve chip yield, fuses of memory devices are typically used in a repair process in which a bad (defective) memory cell is replaced with a redundancy memory cell. As other examples, fuses may be used to customize and/or optimize chip characteristics after fab-out, and fuses may be used to record/indentify chip information and/or fabrication histories.
Fuses may be classified as either laser fuses or e-fuses. Laser fuses are configured to be selectively programmed (that is, opened) by utilization of a laser, and e-fuses are configured to be selectively programmed by utilization of electric current.
Since propagating depth of a laser is limited, laser fuses are disposed at or near an exposed surface. Thus, for example, laser fuses must be programmed before formation of an opaque passivation layer (e.g., epoxy) which may cover or encapsulate a semiconductor chip. As a result, laser fuses cannot be used for chip customization and/or optimization after fab-out. Further, laser programming of fuses requires an expensive laser device and a relatively long programming time.
In contrast, e-fuses have the advantage of being programmable after fab-out, and programming can be conveniently executed during electrical testing of the chip and without the need for an expensive laser device.